If someone were to come along, dig a moderately deep hole in my garden, give me a metal box and tell me I had half an hour to put together a 2006 time-capsule, Jonathan Raban's new novel is the first thing I'd grab. Also to be interred would be an iPod (anyone's but mine), a copy of Golf Punk magazine (also someone else's) and Paris Hilton, should she be in the South London area. But nothing else would come as close to distilling the particular attitudes and anxieties of our time as Surveillance

The basic set-up is very similar to that of Don DeLillo's Mao II (published in 1991) - a novel that made a definite leap forwards into what is now the present. Mao II centres on a reclusive writer tracked down by a photographer; Surveillance centres on a reclusive writer tracked down by a journalist. However, the differences between the two writers are significant. DeLillo's Bill Gray - a mixture of Pynchon, Salinger and Harold Brodkey - genuinely doesn't want to be discovered. Raban's Augie Vanags, by contrast, is a breezy old wiseacre who has been hidden away by his publishers in the sure knowledge that, if allowed to speak, he will instantly destroy the credibility that has made his Holocaust memoir Boy 381 such a bestseller. "August Vanags," as it is put, "was unworthy of being the author of his own book."

Surveillance is a novel of ideas - political ideas. And one of the ideas it proposes, fairly explicitly, is that the old spectrum of far left, left, centre, right and far right has been replaced by one far more rudimentary: against the War on Terror, uncommitted, for the War on Terror. In this debate, Augie represents the hawkish "For" tendency. '"Unless we can win this war, I'm afraid we're going to see the end of the modern nation state, which ... I happen to believe would be a disaster for mankind." The journalist who tracks him down, Lucy Bengstrom, occupies the hesitant middle. "She oscillated uncomfortably between being somewhat scared and somewhat sceptical, never quite the one or quite the other: an agnostic on this as on so much else, a little envious of the true believers for their easy certitude."

By far the strongest character in the book, though, is Tad Zachary, Lucy's best friend, and surrogate father to her daughter Alida. Tad, himself HIV-positive, has lost his partner, Michael, to Aids. Since then he has spent much of this time finding fuel for his political rage in what Raban calls "the virtual counterworld". Yet what rings truest in this portrait of post-liberal angst is the perverse underbelly of it: "When ... the US military practised besieging American cities with tanks, artillery, and armoured checkpoints in the name of 'quarantine', when the Supreme Court became the brass-knuckled enforcer of the presidential will and whim, what Tad felt was an adrenaline rush of angry elation. It was like getting off on porn, this secret relish for the drama of it all." Tad puts forward the case against the War on Terror, though only to Lucy and her daughter, who spend two weekends at Augie's house on Useless Bay, north of Seattle - Tad and Augie never confront one another directly. Who wins the debate? That is left for the reader to decide. But the book has two germane epigraphs, one which comes from Flaubert's letters: "Folly consists in the desire to reach conclusions."

As a novel, rather than a tract for our times, the main problem with Surveillance is not that it is finally inconclusive. How could it be anything else? It is that the inconclusive end does not fit with the bulk of the book, which draws conclusions with almost every sentence. Some of the sub-plots, including one relating to Lucy's besotted landlord, are very neatly worked through, from start to finish.

Towards the end of the novel, Lucy has a vision of how her profile of Augie should be - not like a traditional article at all. "The judicious tone, the summing up, the obituary-like placing of a terminal period at the end of your subject's 'life', it was all flummery and hokum, the smoke-and-mirrors of the journalist's trade." Instead, it would consist of "snapshots, nothing more, disjointed from one another like the capricious rag-bag of images (some more in focus than others) that every camera-toting traveller returned with from a trip. They wouldn't add up."

Surveillance often reads as if this, or something very similar, was Raban's initial vision for what he was going to write. But, in the event, he either couldn't or wouldn't follow through. As its title suggests, spying, and being spied upon, is the one of the novel's main themes. Tad puts it squarely: "We're all spooks now. Look at the way people Google their prospective dates. Everybody does it. Everybody's trying to spy on everybody else." A CCTV camera, though, will only show you what someone is doing. It takes a novel to take you inside their head and show you why they're doing it. Surveillance is as good a way of any of spying on your fellow Americans - and we're all Americans, now.